Dynamics of a Memory Trace: Effects of Sleep on Consolidation Claire Jackson, Brian J. McCabe, Alister U. Nicol, Amanda S. Grout, Malcolm W. Brown, Gabriel Horn  Current Biology  Volume 18, Issue 6, Pages 393-400 (March 2008) DOI: 10.1016/j.cub.2008.01.062 Copyright © 2008 Elsevier Ltd Terms and Conditions

Figure 1 Experimental Protocol; see Supplemental Experimental Procedures Zero hours is the time at which training began. Upward-pointing arrows indicate the approximate mean time of the midpoints of the neuronal tests NT1 through NT4. Downward-pointing arrows indicate the approximate start times for the procedures indicated in the boxes. The following labels are defined: Train, training session; NT, neuronal test; and Pref, preference test. “Rest” and “Disturbed” refer to treatment conditions; “Session” refers to the first 6 hr (session 1) or second 6 hr (session 2) of treatment. Current Biology 2008 18, 393-400DOI: (10.1016/j.cub.2008.01.062) Copyright © 2008 Elsevier Ltd Terms and Conditions

Figure 2 Neuronal Responsiveness in the Rest First and Disturbed First Groups Neuronal responsiveness to the imprinting stimulus (IS) is similar in the Rest First and Disturbed First groups until test NT4, when IS-responsiveness is significantly greater in the Rest First group. There were five chicks in each group. Mean percentage (±SEM) of neurons in each group responding selectively to a stimulus are shown for the stated neuronal test NT1–NT4 (numbers of neurons are given in Table 1). The approximate mean times of the midpoints of the neuronal tests are indicated by arrows. The times of the training periods (Train1 and Train2) and of the treatment sessions are indicated by the horizontal bars. Filled black squares with a continuous line running through them represent the Rest First group; unfilled circles with a broken line running through them represent the Disturbed First group. Under “Overall Neuronal Population,” (A) shows neurons selectively responsive to the imprinting stimulus (IS neurons). (B) shows neurons selectively responsive to the alternative visual stimulus (Avis neurons). Under Tracked neurons, (C) shows IS neurons. (D) shows Avis neurons. Group means in (A) and (C) respectively are significantly different only at NT4. Current Biology 2008 18, 393-400DOI: (10.1016/j.cub.2008.01.062) Copyright © 2008 Elsevier Ltd Terms and Conditions

Figure 3 Numbers of Tracked Neurons in the Four Neuronal Tests that Either Were, or Were Not, Specifically Responsive to the Imprinting Stimulus In the Rest First group, but not the Disturbed First group, a majority of neurons that respond specifically to the imprinting stimulus at test NT1 or NT2 are similarly responsive at test NT4. Individual neurons tracked across neuronal tests NT1 through NT4. The dotted arrow path tracks neurons that responded specifically to the imprinting stimulus (IS neurons) at NT1. The solid arrow path tracks neurons that were not IS neurons (NIS neurons) at NT1. Italicized numbers of IS neurons at NT4 were IS neurons at NT1 or NT2. (A) shows the Rest First group. (B) shows the Disturbed First group. Current Biology 2008 18, 393-400DOI: (10.1016/j.cub.2008.01.062) Copyright © 2008 Elsevier Ltd Terms and Conditions

Figure 4 Mean Percentage, ± SEM, of Energy in Stated EEG Frequency Bands during the Rest and Disturbed Treatments The EEG during the rest treatment is characterized by a higher percentage of energy at 5–6 Hz, and less energy in the range 9–24 Hz, relative to the disturbed treatment. The levels of significance are for comparison of these two treatments. (A) shows the total percentage of energy in each frequency band. (B) shows the subdivision of the 5–8 Hz band into 5–6 Hz and 7–8 Hz components. The rest and disturbed treatments differed with respect to 5–6 Hz but not 7–8 Hz. Current Biology 2008 18, 393-400DOI: (10.1016/j.cub.2008.01.062) Copyright © 2008 Elsevier Ltd Terms and Conditions

Figure 5 Mean Percentage, ± SEM, of Energy in the 5–6 Hz EEG Frequency Band The Rest First group, receiving the rest treatment during session 1, exhibited a time-dependent increase in low-frequency theta activity relative to the Disturbed First group, which received the disturbed treatment during session 1. No such difference between Rest First and Disturbed First was observed during session 2. (A) shows the mean percentage (±SEM) of energy in the 5–6 Hz EEG frequency band during the two sessions. There was a significant interaction between group and session (F1,16 = 14.90, p = 0.001). In the Rest First group, energy declined significantly between session 1 and session 2 (t = 2.28, 16 df, p = 0.037), whereas in the Disturbed First group, energy increased significantly between session 1 and session 2 (t = 3.17, 16 df, p = 0.006). (B) and (C) show data from session 1 and session 2 respectively, subdivided into 1 h blocks. The black bars represent the Rest First group, and the white bars represent the Disturbed First group. Current Biology 2008 18, 393-400DOI: (10.1016/j.cub.2008.01.062) Copyright © 2008 Elsevier Ltd Terms and Conditions